From: Pan Bian <bianpan2016@163.com>
To: Jan Kara <jack@suse.com>
Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
Pan Bian <bianpan2016@163.com>
Subject: [PATCH] ext2: fix potential use after free
Date: Sun, 25 Nov 2018 08:58:02 +0800 [thread overview]
Message-ID: <1543107482-97334-1-git-send-email-bianpan2016@163.com> (raw)
The function ext2_xattr_set calls brelse(bh) to drop the reference count
of bh. After that, bh may be freed. However, following brelse(bh),
it reads bh->b_data via macro HDR(bh). This may result in a
use-after-free bug. This patch moves brelse(bh) after reading field.
Signed-off-by: Pan Bian <bianpan2016@163.com>
---
fs/ext2/xattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 62d9a659a..dd8f10d 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -612,9 +612,9 @@ bad_block: ext2_error(sb, "ext2_xattr_set",
}
cleanup:
- brelse(bh);
if (!(bh && header == HDR(bh)))
kfree(header);
+ brelse(bh);
up_write(&EXT2_I(inode)->xattr_sem);
return error;
--
2.7.4
next reply other threads:[~2018-11-25 0:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-25 0:58 Pan Bian [this message]
2018-11-27 9:19 ` [PATCH] ext2: fix potential use after free Jan Kara
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